From the Yenisei to the Yukon: Interpreting Lithic Assemblage Variability in Late Pleistocene/Early Holocene Beringia

10. The Beringian and Transitional Periods in Alaska: Technology of the East Beringian Tradition as Viewed from Swan Point

179 10. The Beringian and Transitional Periods in Alaska Technology of the East Beringian Tradition as Viewed from Swan Point charles e. holmes S wan Point provides an opportunity to study a Beringian-age archaeological assemblage deep in the interior of Alaska. The site is located in the middle Tanana Valley about 100 km southeast of Fairbanks and occupies a small knoll in the Shaw Creek drainage , a small tributary of the Tanana River (figure 10.1). When the knoll was first occupied, its inhabitants would have had an unobstructed vantage point to observe the surrounding landscape for several kilometers. Unlike the forested landscape of today, the landscape at the close of the Pleistocene would have been treeless, characterized as herb/shrub tundra with considerable amounts of sedges and grasses (Bigelow and Powers 2001). Guthrie has described these conditions as the “mammoth steppe” (Guthrie 2001). A cultural system with emphasis on microblade and burin technology was employed for thousands of years across greater Beringia, where the composite organic projectile point with microblade insets was central to the hunting of high-ranked animals such as mammoth, bison, and horse. This Siberian-based technology is recognized in eastern Beringia at Swan Point between 14,440 and 13,550 cal BP, and it proved to be an efficient adaptation to the environmental conditions of the mammoth steppe. Faunal data recovered from the site suggest that horses and mammoths were hunted at this early timeframe in central Alaska. Before the discovery of Swan Point, the oldest archaeological sites in eastern Beringia with acceptable dating appeared just prior to the Younger Dryas period and did not show strong technological similarities to early microblade cultures in western Beringia. The oldest sites, found in the Nenana Valley, were non-microblade sites with bifacial tools, unlike sites in Siberia. After the report of microblades at Swan Point (Holmes 1998; Holmes et al. 1996), along with radiocarbon dates as early as those from the Nenana sites, some archaeologists questioned the validity of the age and associations (Dixon 1999; Goebel et al. 2003; Hamilton and Goebel 1999; Yesner and Pearson 2002). Concerns were raised about the association of artifacts and a pebbly layer. Tom Dilley characterized the pebbly layer as colluvium (Dilley 1998:145, 150, Table 3.9), which has given a wrong connotation. The site is on the nearly flat top of a hill, and the “pebbly layer” contains unsorted rock fragments of uniform lithology that show little or no sign of physical transport. This layer is best described as containing weathered bedrock rubble. The stratigraphy at Swan Point (figure 10.2A) is straightforward and has been described in detail elsewhere (Dilley 1998): (1) there was an exposed bedrock knoll during a time of active sand dune buildup in the region ; (2) loess accumulation began on top of weathered bedrock rubble fragments of deflation lag that often exhibit wind polish and attests to higher wind energy during the previous period; (3) the loess accumulation rate was initially high, but the rate decreased between the midHolocene and present (figure 10.3). A patchy paleosol at the base of the loess is evidence of early soil formation. This is followed by several paleosols in the middle loess that appear as thin, discontinuous, organic stringers associated with the coarsest-grained section of the loess, up to 50 sand. The upper loess contains the Subarctic Brown Forest soil. Organizing the Past: Sometimes You Have to Get Out of the Pit and Look Around The archaeological record at Swan Point spans the past 14,000 years and is divided into five cultural zones (CZ) Figure 10.1. Location of the Swan Point site and other sites mentioned in text. Beringian and Transitional Periods in Alaska 181 within five prehistoric periods (figure 10.2B) proposed for interior Alaska (Holmes 1995, 2001). The periods are a simple device for dividing time into culturally neutral units as background to the diverse cultural divisions in Alaskan archaeology. The Beringian period covers the time when Siberia was connected to Alaska. The Transitional period includes the disappearance of the land bridge, climate change, and shift in vegetation mosaics (resulting in the Younger Dryas interval, opening of the ice-free corridor, and extinction of Pleistocene animals, e.g., mammoth and horse). The three phases of the Taiga period (Holmes 2008) cover the establishment, development , and continuance of the boreal forest. The Beringian period and the distinctive technology that marks...